The CO 2 , which is a byproduct of the coal the blast furnace consumes, is . Martin Pei, chief tech officer at SSAB (the company that owns the Lulea plant), says that for every tonne iron, the furnace produces 1.6 tonnes CO 2 ,. There are hundreds of blast furnaces like this around the world, with many emitting higher levels. Other energy-intensive processes in the industry make steel-making a significant contributor to greenhouse-gas emissions. This is comparable to the exhaust from all passenger cars worldwide.
A few hundred metres from the Lulea furnace, there is a smaller furnace that produces iron with less carbon pollution. This pilot technology replaces the use of coal with hydrogen and releases only water vapour. Pei states that this is the new way to produce steel and can in principle eliminate all carbon dioxide.
The hydrogen-to-steel process isn’t completely pollution-free. Other steps in the conversion of iron to steel still produce some CO ,, and the iron ore has to be mined. This site produced the first ‘green steel’ in the world last year. It was made with hydrogen using the abundant low-carbon electricity from Sweden, which was generated from nuclear, hydropower, and wind. The pilot plant is owned by HYBRIT, a joint venture that SSAB formed in 2016 with Swedish utility company Vattenfall and LKAB, the national mining company.
Hybrid is expected to help reduce carbon emissions in the world’s economy in a number of ways. Although hydrogen has been touted as a fuel for transportation, it is unlikely to have a significant impact on heating and other sectors. Instead, batteries and electricity provide better low-carbon solutions. Hydrogen’s greatest contribution will be to industrial processes, including plastics, fertilizers, and refining hydrocarbons. These industries are traditionally thought to be more difficult to decarbonize and have received less attention from policymakers, investors, and the media.
Hydrogen might find uses in energy production, too. Hydrogen-based liquid fuels could one day power shipping and air travel. Hydrogen could also be used to reduce carbon emissions in the electricity grid. Excess solar or wind power could be used to make the gas, which could be used in other industrial processes and stored energy. This is how hydrogen could be used to bridge many sectors of the economy.
“Hydrogen “is sort of unique because of how you can produce it and the ways in which it can be used,” says Dharik Ballapragada, a chemical engineering student at the Massachusetts Institute of Technology in Cambridge.
Policymakers eager to achieve net-zero emission goals have launched a massive push towards hydrogen, particularly in the United States and Europe. They subsidize low-carbon hydrogen prices in some cases. In others they give tax credits to hydrogen producers and industries that use it.
Partly because of this boom in investment in hydrogen projects. The Hydrogen Council, an industry group in Brussels, estimates that the hundreds of large-scale hydrogen projects announced already amount to a possible investment of US$240 billion by 2030 — although so far, only one-tenth of these are fully completed deals. By 2050, the council thinks the market for hydrogen and hydrogen technologies will be worth $2.5 trillion per year.
Analysts project that the world will experience a five-to sevenfold increase in hydrogen production between now and mid-century (see “Hydrogen sources”). This will help reduce the world’s carbon footprint, but only if hydrogen production is not influenced by CO 2 emissions.
Hype was a hydrogen-related topic before. Experts believe that hydrogen will succeed because of the amount of money involved. Analysts say that the transition does not require any new technology. However, scientific advances could help speed it up.
” The hydrogen revolution is taking place — this time it’s real,” Oleksiy Tatarenko (economist at the Rocky Mountain Institute, RMI), a Boulder-based sustainability think tank, says.
Where to begin?
Hydrogen is already a significant and polluting industry. The International Energy Agency (IEA) estimates that around 94 million tonnes (Mt) of the gas is made each year. Nearly all of it is made from fossil fuels like natural gas. Natural gas contains methane (CH 4 )) which reacts with oxygen to produce hydrogen molecules and CO 2 HTML3. The latter is then vented into the atmosphere — 900 million tonnes of it each year, or more than 2% of world CO2 emissions, comparable to the total annual emissions of Indonesia and the United Kingdom combined. This polluting hydrogen is called “grey” by analysts.
The hydrogen that the world produces is used mainly for chemical processing in essential industries. It is mixed with nitrogen from the air to make ammonia (NH3), for instance, an ingredient in fertilizer. Hydrogen is used in petrochemical refineries to remove sulfur from petroleum or to reduce some of the larger hydrocarbons in petroleum. And in the chemical industry, hydrogen goes into making massive amounts of products, such as methanol (CH3OH), which in turn is used in the synthesis of countless other chemical commodities.
“Before hydrogen is positioned as the solution to climate change, we have to first deal with hydrogen’s problem in climate change,” stated Michael Liebreich, an energy consultant in London and chief executive at Liebreich Associates, in a keynote address at the World Hydrogen Congress, Rotterdam, the Netherlands in October.
Some CO 2 that is produced by hydrogen production from fossil fuels could possibly be captured and stored underground in deep geological reservoirs. This is how hydrogen can be decarbonized and called “blue”. Critics of blue hydrogen argue that it doesn’t stop all CO 2 emissions and that blue hydrogen is still a way to extract natural gas. This has its environmental downsides.
Another way to make hydrogen is almost entirely carbon-free. This is the 200-year-old technique of water electrolysis: electrolysers extract the H from H2O by running an electric current between catalyst-plated electrodes. The resulting product is known as green hydrogen if the energy used to power it is renewable. Green hydrogen is a potential source of zero emissions or very close to it.
The cost of electrolysers will play a crucial role in the speed at which clean hydrogen can be switched to. The IEA, clean-energy analysts BloombergNEF and other organizations predict that this could fall rapidly — dropping by more than two-thirds by 2030 — as electrolysers are made in increasingly automated assembly lines, rather than built by hand.
Analysts predict that green hydrogen production will cost less than $5 per kilogram, and drop to $1 per kilogram in the future, even if there are no tax breaks or subsidies. This would make it more competitive with grey hydrogen, which can also be made for less than $1 per kilogram (when natural gas prices are not increased as in Europe). Multiple studies have shown that blue hydrogen will be needed to meet the growing demand for hydrogen in the coming decades.
The transformation will require enormous amounts of renewable energy. If electrolysers were 100% efficient, it would take more than 3,000 terawatt hours (TWh) of electricity from renewable sources each year just to replace the grey hydrogen used today with green hydrogen; in reality, the electricity required is more likely to be above 4,500 TWh. This is roughly equivalent to the annual electricity consumption of the United States. What’s more, the IEA envisions a future in which clean hydrogen’s annual electricity requirements rise to 14,800 TWh, in its scenario of a net-zero-emissions world by mid-century.
Still, clean energy is growing at an incredible pace. By 2024, for instance, BloombergNEF projects that the world is expected to have the capacity to produce almost 1 TW of photovoltaic panels each year: that alone could meet one-seventh of today’s annual electricity demand. Overall, the world’s low-emissions electricity supply is already set to more than triple by mid-century, says the IEA — although even more aggressive expansion is needed for a net-zero world in 2050 (see go.nature.com/3nxtvhj).
Steel is the largest sector of industry’s carbon spewers. This sector is where hydrogen could have the greatest impact. Pei says that people had tried hydrogen in this process for years but couldn’t scale it up. But in 2016, right around the time when most countries signed the Paris climate agreement pledging to keep global warming to less than 2 degC above pre-industrial levels, Pei began to spearhead hydrogen research at SSAB. It was obvious that Sweden needed to decarbonize steel in order to fulfill its Paris commitments. SSAB is not a major steel producer, yet it alone accounts for 10% of Sweden’s CO2. Mia Widell, spokesperson for the company, says that everyone knew that SSAB would fail to eliminate those emissions.
Making steel is difficult because it involves extracting iron ore from iron ore, which is essentially iron in an oxidized state. This rust is stripped of oxygen, leaving behind liquid iron. To accomplish this, the ore is combined with coke (a coal derivative) or charcoal. This fuel’s main purpose is not to melt the ore but to grab oxygen atoms. It has a thermodynamic cost that is six times higher than melting the rock. This process results in the release of large amounts of CO 2 ..
SSAB thought of capturing emitted carbon 2 , and storing it underground. But that would be too costly. Instead, it chose to go with the hydrogen pathway. Hydrogen can diffuse inside pellets of solid iron ore and remove oxygen, in a process called direct reduction of iron (DRI), which takes place at 600 degC instead of the more than 1,500 degC of a blast furnace (see ‘Greener steel’).
DRI was in existence long before HYBRIT began using hydrogen for this process. Some steel today is made using natural gas, which causes carbon emissions that clean hydrogen would prevent.
HYBRIT’s Lulea trials were so successful that SSAB decided to move forward the date to shut down its blast furnaces, from 2045 to 2030, says Pei. HYBRIT is building its first full-size plant in Gallivare, a town 200 kilometres north of Lulea, and has made the results of its research publicly available, hoping to create momentum for the whole industry, he says. H2GreenSteel, a Stockholm-based start up company, has already laid the foundations for a larger plant and claims to have sold 1.5 million tonnes of its product ahead of schedule. It is located half an hour from Lulea.
Smelters can last for decades. Energy analysts believe that if countries are to meet the Paris accord goals, they should immediately stop building new blast furnaces. Instead, they should replace them with hydrogen-ready direct reducers. Even though most people initially use natural gas, they can gradually reduce their carbon footprint as hydrogen supply increases over the next three decades.
” There’s no room in the carbon budget to buy new blast furnaces,” said Rebecca Dell, head for the industry programme at ClimateWorks foundation in San Francisco, California.
Many steel producers are moving to DRI, but in China and India new blast furnaces are being built, according to the non-governmental organization Global Energy Monitor. However, the task is so huge that many organizations, including BloombergNEF have predicted that some blast furnaces may still be in operation at mid-century. To reduce their emissions, carbon capture will be required.
In principle steel production could even be electrified, eliminating the need to make hydrogen. This would increase efficiency even further, according to Dell. Many start-ups, including Boston Metal in Woburn (Massachusetts), are exploring the potential of electrolysis to split iron oxide. Hydrogen is still the most popular option. “The greatest advantage of the hydrogen approach to steel-making is that it requires the least amount of technology,” Dell says.
A hydrogen bridge
Over the long-term, hydrogen’s greatest contribution to slowing global warming may be as a bridge between disparate activities, such as electricity, construction, and transport. This makes it more affordable to decarbonize all of these sectors together than if each sector had to do so individually, says Christian Breyer of Lappeenranta Lahti University of Technology in Finland.
The key node in this interconnected web is electricity generation. Hydrogen could be used to address a well-known problem with renewable energy: it is not evenly distributed over the hours and seasons and can often be unpredictable. It is difficult for regions to plan for long periods of time without it.
Researchers involved in simulations to balance demand and supply in future electric grids must plan, for example, how to provide electricity if the wind isn’t blowing for at least a week during a dark, cold winter in Europe. Scientists have a name for this phenomenon: Dunkelflaute, a German word that roughly translates as ‘dark doldrums’.
Batteries will help to balance supply and demand from one hour to the next, but once the share of wind and solar grows past 80% of a grid’s electricity mix, it becomes extremely expensive to make grids resilient to Dunkelflauten, according to some studies (see, for example, J. D. Jenkins et al. Joule 2, 2498-2510; 2018). One option is to build enough wind turbines to power the grid during even the coldest winters and then to use them to make hydrogen for the majority of the year. This hydrogen could then go to industrial customers, such as steel mills or liquid fuels for shipping and export.
In extremely dire times of year, it could also be used to produce electricity again by burning it into turbines similar to those powered on natural gas. However, this would be very wasteful as the grid would only get back one-third to less of the electricity that was used to make the hydrogen.
It’s not clear whether this is the most cost-effective way to decarbonize the last 20% of electricity, compared with building nuclear-power stations or perhaps expanding geothermal energy. Organizations such as the United Nations International Renewable Energy Agency suggest that countries will have different optimal mixes.
Myths and misconceptions
Hydropen has many applications, but that doesn’t mean it is the best solution for all problems. Battery technology has largely prevailed in passenger cars. They are more cost-effective and efficient than transporting hydrogen and then converting it back into electricity.
Another area where hydrogen may not make sense is as a fuel to heat homes. Rebecca Lunn, a civil engineering student at the University of Strathclyde, in Glasgow, UK, said that hydrogen made from grey natural gas will only increase global warming. She and others flagged home heating as a problematic use for hydrogen in a UK National Engineering Policy Centre (NEPC) study, released in September (see go.nature.com/3ut5mj5).
But even if the hydrogen is green — made from renewables-generated electricity — it is up to six times more efficient to use that electricity to heat homes directly using, for instance, heat pumps, which reach efficiencies much higher than 100% by sucking heat in from the outside.
To cut emissions the fastest, policies should prioritize home insulation. This will reduce the need to heat energy from any source, according to Nilay Shah, a researcher at Imperial College London in process-systems engineering, who was the lead of the NEPC study.
Investment has been rising in low-carbon hydrogen for several years. But, this year’s events seem to have triggered what appears to be a real boom.
The Inflation Reduction Act in the United States has created a tax break of $3 per kg of green hydrogen. It also provides funding for a variety of policies and funding pots for the gas. Russia’s aggression against Ukraine in Europe has created a sense of urgency. In March, the European Commission set a target of producing 10 million tonnes of H2, and importing an additional 10 million tonnes, per year by 2030. Other major economies have also developed national strategies to increase hydrogen capacity.
“Everything is different, the whole equation,” said Patrick Molloy, RMI economist. The US tax cuts have brought down the cost of green hydrogen to around $1 per kilogram (or lower depending on where you live) (see ‘Costs for clean hydrogen’). The RMI calculates that this makes hydrogen-based steels, ammonia, and liquid fuels comparable to their fossil-fuel counterparts.
Clean-hydrogen products, such as green steel, can still be more expensive without subsidies. HYBRIT, H2GreenSteel and others do not reveal the expected cost of their products. The government might also consider buying green steel, as Joe Biden’s administration has promised to do under the Buy Clean provision in an executive directive passed last December.
The IEA projects that by 2030, global hydrogen demand might rise by 20-30%. Only about 25% of the low-carbon hydrogen projects in the pipeline will be sufficient to cover that amount. That suggests that hydrogen expansion plans are not yet ambitious enough: for the world to be on track for net-zero emissions by mid-century, some 180 Mt of hydrogen production is needed by 2030, with half of it low-emissions.
But Tatarenko says it is not out of the question that global green-hydrogen production could reach what’s necessary in 2030. “We should be super ambitious .”
Some warn that the push to hydrogen could lead to an increase in non-green hydrogen and a perverse increase in CO emissions. A controversial measure being considered by the European Commission would allow green hydrogen to be produced partly with electricity from fossil fuels.
Reorganizing an economy to accommodate hydrogen will have social repercussions. Heavy industry in certain regions will remain at a competitive disadvantage despite massive investment and subsidies. According to Dell, hydrogen is more costly and more difficult to transport than coal. This means that industries like steel-making may have to move closer to hydrogen-producing sites. “They might even be in different countries .”
Although these and other political issues may slow down the pace, there are no unsolvable problems, she says. Dell says, “This transition is possible within our technical and economic capabilities, both in high-income and emerging economies.”
This article is reproduced with permission and was first published on November 16 2022.